<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <!-- skew  负数就是反方向  transition 1s all width height ease  ease-in(速度越来越快)  ease-out(速度越来越慢) ease-in-out(有个加减 ease默认的形式)-->
  <!-- 时间 样式 形式 -->
  <style media="screen">
    .box {
      width:300px;
      height:300px;
      background:#CCC;
      margin:100px auto 0;
      transition:1s all ease;
    }
    .box:active{
      width:400px;
    }
  </style>
</head>
<body>
<div class='box'>这是一些文字</div>
</body>
</html>
